Field of the Invention
Embodiments of the invention generally relate to a process kit for a semiconductor processing chamber, and a semiconductor processing chamber having a kit. More specifically, embodiments of the invention relate to a process kit including a cover ring, a shield, and isolator for use in a physical deposition chamber.
Description of the Related Art
Physical vapor deposition (PVD), or sputtering, is one of the most commonly used processes in the fabrication of electronic devices. PVD is a plasma process performed in a vacuum chamber where a negatively biased target is exposed to a plasma of an inert gas having relatively heavy atoms (e.g., argon (Ar)) or a gas mixture comprising such inert gas. Bombardment of the target by ions of the inert gas results in ejection of atoms of the target material. The ejected atoms accumulate as a deposited film on a substrate placed on a substrate support pedestal disposed within the chamber.
A process kit may be disposed in the chamber to help define a processing region in a desired region within the chamber with respect to the substrate. The process kit typically includes a cover ring, a deposition ring, and a ground shield. Confining the plasma and the ejected atoms to the processing region helps maintain other components in the chamber free from deposited materials and promotes more efficient use of target materials, as a higher percentage of the ejected atoms are deposited on the substrate.
Although conventional ring and shield designs have a robust processing history, the reduction in critical dimensions brings increasing attention to contamination sources within the chamber. As the rings and shield periodically contact each other as the substrate support pedestal raises and lowers between transfer and process positions, conventional designs are potential source of particulate contamination.
Moreover, the ability to control gas distribution within the chamber contributes to both the quality and uniformity of deposited films. Cover rings are typically centered relative to the pedestal leading to non-uniform gaps created between the cover ring and the shield leading to non-uniform gas distribution. Further, cover rings typically do not allow for variation in the distance between the target and the substrate. Also in previous designs, the surface of the substrate is at or near the top of the cover ring, which causes reactive species to concentrate near the edges of the substrate.
Therefore, there is a need in the art for an improved process kit.